Paxite is a rare copper arsenide mineral typically occurring as massive or granular aggregates in hydrothermal veins. It is most commonly found alongside other copper-arsenic minerals such as koutekite and domeykite. Identification is difficult without laboratory analysis like X-ray diffraction or electron microprobe study due to its resemblance to other silver-white metallic minerals.

Hardness

3.5-4

Mohs

Luster

Metallic, tarnishing black

Streak

Black

Transparency

Opaque

mineralrare

Paxite

Hardness: 3.5-4
Luster: Metallic, tarnishing black
Streak: Black
Transparency: Opaque

Is this paxite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch paxite with a known reference. Paxite sits at Mohs 3.5-4, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: black.
3
Read the luster
Hold the specimen under a strong light. Luster: metallic, tarnishing black.
4
Match the color range
Compare against the expected color range: black, steel gray.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: massive.

Often confused with

Paxite vs. its common look-alikes, and how to tell them apart in the field.

How to tell apart: Streak differs, so Paxite leaves black, Arsenic leaves tin-white; luster reads metallic, tarnishing black on Paxite and nearly metallic on Arsenic.

Compare →

Often found alongside paxite

Minerals reported to co-occur with paxite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: CuAs₂
Mohs hardness: 3.5-4
Density: 5.4 g/cm³
Colors: Black Steel gray
Streak: Black
Luster: Metallic, tarnishing black
Transparency: Opaque
Crystal system: Monoclinic
Crystal habit: Massive
Cleavage: Perfect along {010}
Rarity: Rare
Uses: Collector
Host rock: In hydrothermal calcite veins cutting diopside hornfels lenses, in pyroxene gneisses and mica schists

Where rockhounds find paxite

Classic worldwide localities

Mohawk, Keeweenaw Co., Michigan, USA
Černý Důl mine, Krkonoše (Giant Mountains), Czech Republic (type locality)
Mühltal, Niederbeerbach, Odenwald, Hesse, Germany

Field-hunting tip

Where it forms: In hydrothermal calcite veins cutting diopside hornfels lenses, in pyroxene gneisses and mica schists. If you start seeing novákite, koutekite, arsenic in float, you are in the right ground. Typical habit: massive. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify paxite?+

Mohs hardness is 3.5-4. Luster: metallic, tarnishing black. The streak is black. Common colors include black, steel gray.

Where is paxite found?+

Notable localities include Mohawk, Keeweenaw Co., Michigan, USA; Černý Důl mine, Krkonoše (Giant Mountains), Czech Republic (type locality); Mühltal, Niederbeerbach, Odenwald, Hesse, Germany.

Is paxite safe to handle?+

Paxite contains arsenic and copper and calls for real care. Contains arsenic, a toxic element. Wash hands thoroughly after handling and avoid inhaling dust during specimen preparation.

What rocks look like paxite?+

Paxite is most often confused with Domeykite, Koutekite, Arsenic. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with paxite?+

Paxite commonly co-occurs with Novákite, Koutekite, Arsenic, Arsenolamprite, Silver, Löllingite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does paxite form in?+

Where it forms: In hydrothermal calcite veins cutting diopside hornfels lenses, in pyroxene gneisses and mica schists. Working float back to the host body is the standard way to chase a fresh occurrence.

What is paxite used for?+

Paxite is used in collector.

Find paxite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.